A 12-year-old boy presented to the pediatric cardiology outpatient department with chief complaints of dyspnea on exertion (NYHA grade II) for the past 2 years. Transthoracic echocardiography revealed atrioventricular and ventriculoarterial discordance suggestive of a congenitally corrected transposition of great arteries (ccTGAs) with a ventricular septal defect (VSD) and severe subvalvular pulmonic stenosis.
A cardiac computed tomography angiography was performed for further delineation of the cardiovascular morphology which confirmed the echocardiographic diagnosis of ccTGA. It also depicted an aneurysm of the membranous part of the interventricular septum which was seen bulging into the subpulmonic region, akin to a windsock, causing significant stenosis of the morphologically left ventricular outflow [Figure 1]. There was a small defect in the bulging membranous interventricular septal aneurysm resulting in an interventricular communication. The aneurysm of the membranous part of the interventricular septum had no attachments to the right-sided atrioventricular valve or the valve mechanism.
Figure 1.
Oblique axial image (a), oblique coronal image (b) and volume rendered image (c) of computed tomography angiography along with the schematic representation (d) demonstrate atrioventricular and ventriculoarterial discordance along with an aneurysm (*) of membranous interventricular septum which is seen bulging into the subpulmonic region causing morphological left ventricular outflow obstruction. A small defect (indicated by the black arrow in panels b-d) is noted in the bulging membranous interventricular septal aneurysm resulting in an interventricular communication. A: ascending aorta; LA: left atrium; LV: left ventricle; P: main pulmonary artery; RA: right atrium; RV: right ventricle
ccTGA is a rare congenital heart disease accounting for approximately 0.5% of all congenital heart defects (CHDs) and is characterized by double inversion (atrioventricular and ventriculoarterial discordance) with an associated VSD seen in 70%–80% of cases.[1] A membranous interventricular septal aneurysm has been reported in 0.3% of all CHDs and is associated with a VSD in 1/5th of all cases.[2] Membranous interventricular septal aneurysms are known to be associated with outflow tract obstruction, rupture of the aneurysm, conduction abnormalities, and thromboembolism.
Association of ccTGA with membranous interventricular septal aneurysm causing subpulmonic obstruction is exceedingly rare. In patients with ccTGA, secondary to the parallel arrangement of the ascending aorta and main pulmonary artery and the respective outflow tracts, the membranous part of the interventricular septum lies in proximity to the morphologically left ventricular outflow (subpulmonic region). Since the pressure is higher in the morphologically right ventricle compared to the morphologically left ventricle, the membranous interventricular septal aneurysm bulges toward the morphologically left ventricular outflow (windsock syndrome) causing its narrowing resulting in the subpulmonic stenosis.[3] In the present patient, surgical repair in the form of a double switch operation with resection of the membranous septal aneurysm and closure of the defect was proposed. However, the patient’s parents refused surgery on account of the morbidity associated with the surgery and that the patient was otherwise doing well on follow-up with only NYHA grade II dyspnea.
Declaration of patient consent
The authors certify that they have obtained all appropriate patient consent forms. In the form, the legal guardian has given his consent for images and other clinical information to be reported in the journal. The guardian understands that names and initials will not be published and due efforts will be made to conceal patient identity, but anonymity cannot be guaranteed.
Conflicts of interest
There are no conflicts of interest.
Funding Statement
Nil.
REFERENCES
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